"... that's number 1, number 2, and now number 7 that have come down from
this explosion and folks just simply can't believe it. ... I just never for the
life of me imagined that these huge buildings would just fall, and that's what
happened, they just crumbled." [338kB wma
download]

"I remember getting a call from the, er, fire department commander, telling
me that they were not sure they were gonna be able to contain the fire, and I
said, 'We've had such terrible loss of life, maybe the smartest thing to do is
pull it.' And they made that decision to pull and we watched the building
collapse."

The building fire alarm system [for WTC 7] was placed on TEST for a period of 8 h
beginning at 6:47:03 a.m. on September 11, 2001. Ordinarily, this is requested when maintenance or other
testing is being performed on the system, so that any alarms that are received from the system are considered
the result of the maintenance or testing and are ignored. [NIST]

Heavy duty explosives were in WTC 7 on 9/11:

After the initial blast [Flight 11 hitting WTC 1], Housing Authority worker Barry
Jennings, 46, reported to a command center on the 23rd floor of 7 World Trade Center. He was with Michael
Hess, the city's corporation counsel, when they felt and heard another explosion. First calling for help, they
scrambled downstairs to the lobby, or what was left of it. "I looked around, the lobby was gone. It looked
like hell," Jennings said. [Traverse
City Record Eagle 9/11/2001]

Michael Hess 9/11 interview

Barry Jennings interview

"Seven is exploding..."

Firemen evacuated the area as they prepared for the collapse of Building Seven. [Ground Zero Spirit]

"That building right there, the brown building, the tall one, is
number 7 World Trade Center."

"We've heard several reports from several
different officers now that that is the building that is going to go
down next."

"In fact one officer told me they're just waiting for that to
come down at this point."

The official NIST explanation for the cause of the collapse is summarised as
follows:

The heat from the uncontrolled fires caused steel floor
beams and girders to thermally expand, leading to a chain of events that caused
a key structural column to fail. The failure of this structural column then
initiated a fire-induced progressive collapse of the entire building. [NIST]

This explanation is fundamentally flawed:

A close look at the collapse of WTC 7 offers a valid
explanation for the building's demise:

The building collapsed perfectly into its footprint at
freefall speed.

Sometimes ... a building is surrounded by structures that
must be preserved. In this case, the blasters proceed with a true implosion,
demolishing the building so that it collapses straight down into its own
footprint (the total area at the base of the building). This feat requires such
skill that only a handful of demolition companies in the world will attempt it.
[HowStuffWorks]

...but we are supposed to believe fires perfectly imploded WTC 7.

Are you
kidding me?

There can be only one conclusion as to what happened to WTC 7 - it
was demolished.